Gas fuel supply system



Nov. 21, 1961 Filed June 9, 1958 F. BARFOD GAS FUEL SUPPLY SYSTEM 2 Sheets-Sheet 1 INVENTOR. FREDERIK BARF-OD AT TORN EY 2 Sheets-Sheet 2 Filed June 9, 1958 0/0 0 1 1 f 0 ,w 0 5 F I/ M MM 0 A0 INVENTOR. FREDERIK BARFOD BY AT TURN EY United States Patent 3,009,794 GAS FUEL SUPPLY SYSTEM Frederik Barfod, Detroit, Mich., assignor to The Bendix Corporation, a corporation of Delaware Filed June 9, 1958, Ser. No. 740,725 Claims. (Cl. 48184) The present invention relates generally to gas fuel supply systems for an internal combustion engine and more particularly to an improved liquified petroleum gas carburetor for such systems.

Liquified petroleum gas, hereinafter referred to as L.P.G., systems usually include a storage tank, vaporizer, pressure regulator and a carburetor. Gas is delivered under positive pressure to the carburetor where it is metered to supply engine requirements.

In some prior L.P.G. systems difficulties have been experienced in obtaining (a) sufficient pressure differential across the metering restriction to accurately meter the fuel throughout the operating range of the engine; (b) smooth transition from the idle system to the main system; and (0) quick response in the system to provide fuel for acceleration.

The present invention has as an object to provide in an L.P.G. supply system means for improving the metering, the idle to main system transition and the response time of the system.

It is a further object of the invention to provide a control for an L.P.G. fuel supply system having relatively few parts which may be inexpensively manufactured and which is accurate and reliable in operation.

These and other objects of the invention will become readily apparent from the following description and drawings wherein:

FIGURE 1 is a view of an L.P.G. fuel supply system with a carburetor of the present invention shown in its operative position;

FIGURE 2 is a schematic view of an L.P.G. carburetor embodying the present invention; and

FIGURE 3 is a schematic view of another embodiment of my invention in an L.P.G. carburetor.

Referring now to the drawings, numeral ltl designates a storage tank, 12 a fuel vaporizer, 14 a pressure regulator, 16 a carburetor for supplying fuel/air mixture ratio to the engine 18. As best seen in FIGURE 2, carburetor 16 is provided with an induction passage 20- having a venturi 22 formed therein. A choke valve 24 is mounted in the induction passage 20 adjacent the inlet thereof; and a throttle valve 26 is mounted in the induction passage downstream of venturi 22. A flange 28 is formed on the carburetor adjacent the outlet of the induction passage for mounting the carburetor on the engine by suitable bolts 29.

A housing 30 is formed on the carburetor and contains marginally clamped first and second diaphragms or movable walls designated respectively by numerals 32 and 34. The diaphragms are centrally connected by a spacer member 36 whereby the diaphragms are adapted to move as a unit. The diaphragms 32 and 34 divide the interior of housing 36 into first, second and third chambers designated respectively 38, 4t) and 42. The first chamber 38 is provided with a port 44 which is connected to the storage tank or source of fuel by a conduit 46. A valve 43 operatively connected to diaphragm 32 by levers 50 and 52 is located to seat on port 44 and control the how of fuel through conduit 46 into the first chamber 38. A spring 54 is connected to the central portion of diaphragm 34 at one end and at the other end is connected to an adjustable member or screw 56. Spring 54 is disposed to urge valve 48 toward closed position and is 3,909,?94 Patented Nov. 21, 196i adjusted so as to exert a predetermined force on the diaphragms. The main metering restriction 58 is formed in a side wall of chamber 38 and is connected by a conduit 6;"; with discharge port 62 located at the throat of venturi 22. A passageway 64- connects chamber 40 with the induction passage 20 downstream o-r posterior to the throttle 26. An idle restriction 66 is formed in passageway 64 and is provided with an adjustable needle valve 68 for controlling the flow therethrough. A passage 76 provided with a calibrated restriction 72, connects conduit 60 intermediate discharge port 62 and main metering restriction 58 with passageway 64 anterior the idlle restriction 66.

Chamber 42 is connected to the induction passage 20 anterior the choke valve 24 by means of conduit 74. In some installations, however, the conduit 74 may open directly to the atmosphere rather than to the induction passage 20.

In operation, when the engine is idling the throttle is in closed or substantially closed position and a high manifold vacuum is applied to the idle jet or restriction 66 whereby air will flow from chamber 40 and from venturi 22 through discharge outlet 62, conduit 66 and restrictions 72. In the example shown, when sutficient air has been withdrawn from chamber 40 to reduce the pressure therein to approximately one-fourth inch of water, diaphragm 34, which has an area larger than the area of diaphragm 32, will be moved to the right in opposition to spring 54 to open the fuel inlet valve 48 thereby permitting L.P.G. fuel to flow into chamber 38. L.P.G. fuel in chamber 38 will flow through the main metering restriction 58 via conduits 6t) and 70, restriction 72, passageway 64, idle restriction 66 to the induction passage 20 downstream of the throttle. A portion of the fuel flowing through the main metering restriction 58 during idling will be discharged through the main discharge port 62 directly into the venturi. The pressure in conduit 60 on the downstream side of the main metering restriction 58 will assume a value between the pressure in the venturi 22 and in the chamber 40 depending upon the relative sizes of the discharge port 62 and restriction 72. As shown, the area of the discharge port 62 is considerably larger than the area of restriction 72 so that the pressure on the downstream side of the main metering restriction will more nearly equal the pressurein the venturi rather than in the chamber 46.

As the throttle is opened, the air flow through induction passage 26 increases, causing a reduction in pressure at venturi 22 which acts through discharge ports '62, conduit 70, restriction 72 to reduce the pressure in chamber 40. When the pressure in chamber 40 drops below the value of the pressure in the induction passage downstream of the throttle valve 26, air and/ or fuel/ air mixture will be drawn through the idle restriction 66, restriction 72 and conduit 70 to mix with the fuel discharge through the main metering restriction 58. The relative areas of diaphragms 32 and 34 are such that for each reduction in venturi pressure as applied to chamber 44} there will be an increase in the fuel pressure in chamber 38 of a larger magnitude than the decrease in venturi pressure.

By locating the main restriction 58 so as to discharge between the main discharge port 62 and restriction 72, all the fuel, whether discharged through the idle jet or the main discharge port 62, will be metered by the main metering restriction without any possibility of air being bled into the fuel before passing through the main metering restriction.

Due to the avoidance or reduction of air bleeding and the increase in metering head across the main metering restriction and to the fact that all fuel passes through the main metering restriction, the carburetor embodying the present invention provides better metering characteristics than have been previously obtainable. Furthermore since fuel under positive pressure is always available at the upstream side of the main metering restriction during operation of the engine there is little or no time lag in supplying additional quantities of fuel for acceleration purposes.

While the housing 30 has been described as being formed on the carburetor, it should be understood that the housing may be separate from the carburetor and located in any convenient location such as in the air cleaner or on the firewall of the vehicle.

Referring now to the embodiment shown in FIGURE 3, parts corresponding to those of FlGURE 2 will be designated by a corresponding primed number. inlet valve 48 is urged towards closed position by a calibrated spring 76 which encircles a rod 78 secured at one end to valve 4R8 and provided at its other end with a pin 80 which has a one way connection with a crank 82.. Crank 82 is provided with an arm 84 which abuts the central portion of diaphragm 32'. A cup-shaped spacer member 86 is secured to diaphragm 32' and is adapted to abut the central portion of diaphragm 34'. A spring loaded primer plunger 88 is disposed in the end wall of housing 30 and is so constructed and arranged that when the primer is pushed inwardly to engage diaphragm 34', inlet valve 48, which is operatively connected to diaphragm 32', is opened.

A power enrichment device shown generally at 90 is connected to the fuel chamber 38' by means of conduit 92. The interior of the power enrichment device 99 is divided into two chambers 94 and 96 by a marginally clamped diaphragm 98. Chamber 94 is connected to the annular discharge port 62' by means of conduit 100. A valve centrally secured to the central portion of diaphragm 98 controls the flow of LPG. fuel from conduit 92 into chamber 94. Valve 102 is urged towards open position by a spring 104 disposed in chamber 96. A conduit 106 connects chamber 96 to the induction passage 25) posterior the throttle valve 26 whereby vacuu-m in chamber 96 acts on diaphragm 98 to urge the valve 102 towards closed position in opposition to spring 184.

In operation, upon starting of the engine, the primer rod 88 is pushed inwardly causing the inlet valve 48' to open and permit fuel to flow into chamber 38. Upon the release of the primer rod 88 and creation of a vacuum posterior to the throttle 26' a vacuum will be created in chamber 40' by means of the connection of said chamber with the induction passage via conduit 64' and restriction 66 whereby the inlet valve 48 will be opened permitting L.P.G. fuel to flow into chamber 38 and thence to the idle discharge restriction 66 via main metering restriction 58', conduit 60', restriction 72, conduits 70 and 64'. In some installations an additional idle port 108 may be provided immediately upstream of the throttle valve when the throttle valve is in closed position. When the second idle port 168 is provided it acts as an idle air bleed when the throttle valve is closed and as an idle discharge port when the throttle valve has been opened sufiiciently so that the port is located on the downstream side of the throttle.

When the air flow through the induction passage creates a depression at ventu-ri 22 lower than the depression posterior the throttle the fuel discharge will be transferred from the idle system to the main discharge system comprising main metering restriction 58, conduit 6% and discharge port 62. A needle valve 110 may be provided to adjust the area of main metering restriction .5 8 to calibrate the carburetor to a particular engine and/or to a particular fuel.

During part throttle operation the vacuum in induction passage 20 posterior the throttle 26 will be or a sufficient magnitude as applied to chamber 96 in the power enrichment device 90 to hold the power enrichment valve 02 in closed position. When the manifold vacuum in chamd ber 96 drops below a predetermined value spring 104 urges power enrichment valve 102 towards open position permitting an additional quantity of fuel to be discharged through the discharge port 62 via conduit 100.

Although only two embodiments of my invention have been described, it will be readily apparent to those skilled in the art that changes or arrangements of parts may be made without departing from the spirit of my invention.

I claim:

1. In a gaseous fuel supply system for an internal combustion engine having a source of fuel and an induction passage with a throttle and a venturi therein, a housing, first and second movable walls in said housing defining therein first, second and third chambers, means connecting said first and second walls whereby said walls move as a unit, a port in said first chamber, means adapted to connect said port with said source of fuel, a valve operatively connected to said first wall adapted to control the how through said port, resilient means connected to one of said walls urging said valve toward closed position, a conduit connecting said first chamber to said venturi, a main metering restriction in said conduit, a passageway connecting said second chamber to said induction passage downstream of said throttle, an idle restriction in said passageway, -a calibrated passage connecting said conduit intermediate said main metering restriction and said venturi to said passageway anterior to said idle restriction, and means connecting said third chamber to a reference air pressure.

2. In a gaseous fuel supply system for an internal corn bustion engine having a source of fuel and an induction passage with a throttle and a venturi therein, a housing, first and second movable walls in said housing defining therein first, second and third chambers, means connecting said walls for transmitting movement of one of said walls to the other of said walls, a conduit adapted to connect said first chamber with said source of fuel, a valve operatively connected to said first wall adapted to control the flow through said conduit, a spring connected to one of said walls urging said valve toward closed position, a main metering restriction opening into said first chamber, a discharge port opening into said venturi having a cross-sectional area substantially larger than the cross-sectional area of said main metering restriction, a conduit connecting said main metering restriction with said discharge port, a passageway connecting said second chamber with said induction passage downstream of said throttle, an idle restriction in said passageway, a valve in said passageway for regulating the flow therethrough, a conduit connecting said discharge port with said passageway anterior said idle restriction, a calibrated restriction in said last mentioned conduit, and means connecting said third chamber with said induction passage upstream of said venturi.

3. In a gaseous fuel supply system for an internal combustion engine having a source of fuel and an induction passage with a throttle and a venturi therein, a housing, first and second movable walls in said housing defining therein first, second and third chambers, a member connecting said first and second walls for transmitting movement of one of said walls to the other of said walls, a conduit adapted to connect said first chamber with said source of fuel, a valve operatively connected to one of said walls for controlling the flow through said conduit, a discharge port opening into said venturi, a conduit connecting said discharge port to said first chamber, a main metering restriction in said last mentioned conduit, a passageway connecting said second chamber to said induction passage posterior said throttle, an idle restriction in said passageway, a valve adapted to coact with said idle restriction to control the fiow therethrough, a conduit adapted to connect said discharge port to said passageway anterior said idle restriction, a calibrated restriction in said last mentioned conduit, resilient means operatively connected to one of said walls for urging said first mentioned valve toward closed position, and means for connecting said third chamber to the atmosphere.

4. In a gaseous fuel supply system for an internal combustion engine having a source of fuel and an induction passage with a throttle and a venturi therein, a housing, first and second movable walls it said housing defining therein first, second and third chambers, a port in said first chamber, means adapted to connect said port with said source of fuel, a valve operatively connected to one of said wails adapted to control the fiow through said port, resilient means urging said valve toward closed position, a conduit connecting said first chamber to said venturi, a main metering restriction in said conduit, a passageway connecting said second chamber to said induction passage downstream of said throttle, an idle restriction in said passageway, a calibrated passage connecting said conduit intermediate said main metering restriction and said venturi to said passageway anterior to said idle restriction, and means connecting said third chamher to a reference air pressure such as atmospheric pressure.

5. In a gaseous fuel supply system for an internal combustion engine having a source of fuel and an induction passage with a throttle and a venturi therein, a housing, first and second movable Walls in said housing defining thenein first, second and third chambers, a connection between said walls, means adapted to connect said first chamber with said source of fuel, a valve operatively connected to one of said walls adapted to control the flow through said means, resilient means urging said valve toward closed position, a conduit connecting said first chamher to said venturi, a main metering restriction in said last mentioned conduit, a passageway connecting said second chamber to said induction passage downstream of said throttle, an idle restriction in said passageway, a calibrated passageway connecting said last mentioned conduit intermediate said main metering restriction and said venturi to said passageway anterior to said idle restriction, means connecting said third chamber to a reference air pressure, and a primer member adapted to engage one of said walls to move said valve toward open position.

References Cited in the file of this patent UNITED STATES PATENTS 1,573,079 McKee Feb. 16, 1926 2,258,003 Dickson Oct. 7, 1941 2,314,580 Garretson Mar. 23, 1943 2,754,186 Ensign July 10, 1956 

1. IN A GASEOUS FUEL SUPPLY SYSTEM FOR AN INTERNAL COMBUSTION ENGINE HAVING A SOURCE OF FUEL AND AN INDUCTION PASSAGE WITH A THROTTLE AND A VENTURI THEREIN, A HOUSING, FIRST AND SECOND MOVABLE WALLS IN SAID HOUSING DEFINING THEREIN FIRST, SECOND AND THIRD CHAMBERS, MEANS CONNECTING SAID FIRST AND SECOND WALLS WHEREBY SAID WALLS MOVE AS A UNIT, A PORT IN SAID FIRST CHAMBER, MEANS ADAPTED TO CONNECT SAID PORT WITH SAID SOURCE OF FUEL, A VALVE OPERATIVELY CONNECTED TO SAID FIRST WALL ADAPTED TO CONTROL THE FLOW THROUGH SAID PORT, RESILIENT MEANS CONNECTED TO ONE OF SAID WALLS URGING SAID VALVE TOWARD CLOSED POSITION, A CONDUIT CONNECTING SAID FIRST CHAMBER TO SAID VENTURI, A MAIN METERING RESTRICTION IN SAID CONDUIT, A PASSAGEWAY CONNECTING SAID SECOND CHAMBER TO SAID INDUCTION PASSAGE DOWNSTREAM OF SAID THROTTLE, AND IDLE RESTRICTION IN SAID PASSAGEWAY, A CALIBRATED PASSAGE CONNECTING SAID CONDUIT INTERMEDIATE SAID MAIN METERING RESTRICTION AND SAID VENTURI TO SAID PASSAGE WAY ANTERIOR TO SAID IDLE RESTRICTION, AND MEANS CONNECTING SAID THIRD CHAMBER TO A REFERENCE AIR PRESSURE. 